One of the most serious side effects of cancer chemotherapy is myelosuppression--suppression of production of white blood cells, red cells, and platelets due to damage to the blood-forming elements of bone marrow in mammals. Myelosuppression can result in severe infections or bleeding and can result in death.
Currently, several strategies are employed to reduce this serious side effect. Granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage-colony stimulating factor (GM-CSF), stem cell factor (SCF), erythropoietin (EPO), thrombopoietin (TPO), or interleukin-11 (IL-11) is given to stimulate the bone marrow to produce more white blood cells, red cells or platelets. However, even with these bone marrow stimulating agents, chemotherapy doses cannot be high enough to have significant impact upon patient survival. Therefore, today autologous bone marrow transplant (ABMT) or peripheral blood stem cell (PBSC) transplant are relied upon to reconstitute severely damaged bone marrow. Both autologous bone marrow transplant and autologous peripheral stem cell transplant involve harvesting the patient's own hematopoietic cells, storing them outside the body while chemotherapy is administered to the patient, and then returning the previously-stored cells back to the patient after the chemotherapeutic agents have largely dissipated from the body. These methods provide the advantage of reducing the severity and duration of myelosuppression so that delivery of very high doses of chemotherapeutic agents can be administered.
However, these prior art methods are quite complicated and expensive to perform. Harvesting of a patient's bone marrow cells usually requires general anesthesia to perform multiple needle passes into bone marrow of pelvic bones. Harvesting of peripheral stem cells for PBSC transplant requires multiple apheresis procedures that are expensive and labor-intensive. The proper asceptic processing and freezing of harvested bone marrow cells and peripheral stem cells are also labor intensive and require highly trained laboratory personnel and special laboratory facilities. For these reasons, ABMT or PBSC transplant are not routinely performed in an ordinary oncologist's office making it difficult to perform multiple cycles of chemotherapy with ABMT or PBSC transplant.
To enable broad applicability to the general population of cancer patients, including those without access to expensive and sophisticated medical technologies, it is desirable to have an alternative method of reducing the myelosuppresive effect of chemotherapy that is both less costly and is simple enough to be performed in an ordinary oncologist's office. In addition, to derive the maximum benefit from cytotoxic agents, it is quite desirable to use a procedure that allows administration of multiple cycles of chemotherapy to the cancer patient.
Many cancers are confined to the trunk of the body. If it were possible to restrict arterial flow to the trunk of the body or to shield at least a portion of the myelopoietic bone marrow in the limbs while administering a chemotherapeutic agent to the remainder of the body, the need for removing a portion of the patient's bone marrow to preserve it from the effects of the chemotherapy could be avoided. Conrad et al. (Blood, 16:1089-103, 1960), almost 40 years ago, treated eight cancer patients using a procedure in which tourniquets were applied to three extremities (one arm plus two legs) for 15 minutes while nitrogen mustard was being administered. The chemotherapy involved administration of nitrogen mustard (1.0 to 1.5 mg/kg) under general anesthesia with endotracheal intubation in an operating room. Out of the eight patients treated, two patients died within three days, one from pulmonary embolism and the other from postoperative aspiration pneumonia. All six patients who survived more than three days postoperatively, suffered severe side effects, including headache, tinnitus and local thrombophlebitis, and three of the six patients suffered deafness. One patient died at 78 days post-operatively with internal and external hydrocephalus. The symptoms of the latter patient included aphasia, hemiparesis, papilledema, mental confusion, somnolence, and weakness.
Thus, this prior art method of chemotherapy generated severe side effects. The general anesthesia and intubation used in the study have risks, including aspiration pneumonia and pulmonary embolism, from which two of the eight patients succumbed within three days. Tourniqueting of the lower extremity may have also contributed to the fatal pulmonary embolism in one patient. Besides these side effects, the prior art method is expensive. General anesthesia and intubation are generally performed in an operating room and require presence of an anesthesiologist, artificial ventilation, and monitoring equipment, all of which significantly increase the cost of the chemotherapy treatment
In addition, in adults most of the myelopoietic bone marrow in the upper and lower extremities is confined to the upper 1/3 of the humerus and femur. Since Conrad et al. appear to have used a common tourniquet applied in the usual tourniquet position to practice the prior art method of chemotherapy, it is likely that the myelopoietic bone marrow in the extremities of the patients treated was exposed to the myelosuppresive agent.
Almost 40 years ago in Africa, Duff et al. (British Med J., 2:1523-8. 196 1) also treated patients under general anesthesia on an operating table in a chemotherapeutic method intended to protect the bone marrow from the myelosuppresive effects of the chemotherapeutic method. Sand bags were placed on the patient's abdomen, directly over the aorta, and then the patient's body was tightly wrapped with elastic Esmarch bandage while the chemotherapeutic agent was administered. The occlusion was maintained for 20 minutes and the treatment was repeated 48 hours later.
However, this prior art method of chemotherapy is useful for only a limited number of patients. External compression of the abdomen at a pressure high enough to occlude the aorta is only possible in thin patients and may damage delicate internal organs and anatomic structures in the abdomen and pelvis, such as the intestines, kidneys, bladder and ureters. Abdominal pressure high enough to occlude the aorta would also be likely to occlude the inferior vena cava, possibly causing formation of thrombus in the inferior vena cava or other veins in the pelvis and legs, especially in hypercoagulable cancer patients. In addition to the risks involved, the use of general anesthesia in Duff's method would make it expensive and difficult to apply in the modern era.
The tourniquets of prior art have design limitations which make them difficult to apply to the shoulder area or hip area. They have been designed to be applied to part of the limb which is largely cylindrical or conical, such as the upper arm or thigh areas. Since the areas of active bone marrow in limbs are normally limited to the proximal 1/3 of the humerus and femur, blood circulation must be interrupted in the shoulder area or hip area, not just in the arm or leg area. However, the shoulder and hip areas are of complex three-dimensional shape, and tourniquets designed to apply a uniform pressure to these areas do not exist in prior art, as far as the Applicant is aware. Therefore, methods of tourniquet application and new tourniquet apparatus are needed that are designed for application to the shoulder and hip areas.